Mechanical interlock



June 23, 1953 M. H. sHELDoN 2,542,753

MECHANICAL INTERLOCK Original Filed Oct. 25, 1945 5 Shee'S-Sheet l Uff 4 off June 23, 1953 M. H. SHELDON 2,642,753

' MECHANICAL INTERLOCK Original Filed Oct. 26, 1945 5 Sheets-Sheet 2 June 23, 1953 M. H. sHELDoN 2,642,753

MECHANICAL INTERLOCK Original Filed Oct. v26, 1945 5 Sheets-Sheet 3 n 2Q ga 25 Q n?? INVENTOR.

June 23, 1953 M. H. sHELDoN MECHANICAL INTERLOCK 5 Sheets-Sheet 4 Original Filed Oct. 26, 1945 June 23, 1953 M. H. SHELDON 2,642,753

MECHANICAL INTERLOCK original Filed om. 2e, 1945 5 sheets-sheet 5 IN V EN TOR.

Patented `une 23, 195.3

MECHANICAL INTERL'OCK Malcolm H. Sheldon, deceased, late of Athens,

Pa., by Y Mildred Athens, Pa.

V. Sheldon, adminis'tra'trix,

Original application October 26, 1945, Serial No. 624,621, now Patent No. 2,509,018, dated May 23, 1950. Divided and this application March v30, 1950, Serial No. 152,962

5 Claims. (Cl. 'Z4- 483) (Granted wider Tine 35, U. s. cod-e sec. 266) This invention relates 'to remote control systems and more particularly to a control system used in regulating the lighting Aof airport runways and similar traffic ways. n

An object of this invention is to provide an improved electrical circuit 'for airport runways.

Another object is to provide an electrical c1rcuit that will safeguard against destruction or damage to sensitive electrical elements in said circuit. l K v Another object isto simplify7 the operation of the control system for airport runways or similar traffic lanes.

Another object is to provide 'a simplied control panel for said remote-control system.

Another object is toV provide 'novel locking means to insure proper selection of dia-ls on said simplied control panel. y o

Further objects and advantages of this invention, as well as its construction, arrangement and operation, will be apparent'frcm the following description Vand claims in connection with the accompanying drawings, in which Fig. l is a diagram of the electrical circult of the present invention. Y

Fig. 2 is a front exterior view of the control chassis of said remote control system.

Fig. 3 is a plan view of .the chassis shown vin Figure 2 with the cover plate removed to show clearly the components thereof.

Fig. 4 is an end View of theinterlocking means of my invention as `seen from the rear of .the

chassis. i u A Fig. 5 is a rear View of the brightness selector drum certain portions being omitted from the selector drum for purposes of clarity .Y

In Fig. 1, below the dashed line 9, there 1s shown a circuit generally designated A that supplies electrical energy fromvmain lines I through an oil circuit breaker II, a constant current transformer I2 and auto-transformer I3, and thence through intensity selector relays I4, I5, and I6, and through runway selector relays I'I, I8 I9, and 20, to runway .lighting circuits I, II, III, and IV. A protective relay 2I .is placed in the circuit A to insure that the oil circuit breaker II is deenergized thus to open-circuit circuit A in the event that anyy of the runway lighting circuits along the runways should be broken while a plane crashes in taking olf or landing on the particular runway in use.

The selector system TB shown above line 9 coinprises a switch 22 which, when closed, permits current to ow from a battery or other vsuitable local supply of current through the leads 23,

' ness selector drum` 256 2 lighting 'an indicating lamp 24 on the panel board 25 (Fig. 2) to signal the operator of the selector system that power is available for a brightness selector drum 26. The brightness selector drum 26 (more `clearly shown in Fig. 3) is rotated by the handle T21 on the panel 25.

When the brightness selector drum 26 has been rotated to either of the first three positions shown on the drum 26 (Fig. 1) as by dashed lines .I, 2 and 3, the said positions corresponding to dim, medium and bright intensity, respectively (t-he fourth position shown by dashed line 4 corresponding to medium intensity, its functions to be explained subsequently), the `corresponding indicating or pilot lamp 28, 23, or v30 will signal the operator the particularbrig'htness selected. Similarly, after selection of brightness has been made, the desired runway is selected by turning lthe handle3I (Figs. 2 and 3) that is keyed tothe shaft of a .runway selector drum `V32, with lamps or pilot lights 33, 3'4, 35 and r36 serving to indicate which runway has been selected. The closing of a switch 3l completes the vcircuit betweenthe selector circuit B and the circuit A. the indicating .lamp 38 signaling, when lighted, that the oil circuit fbreaker II has been closed and .that the lights of a desired' runway have been energized.

.A mechanical interlock, shown in Figs. 3 and 4, connects the |brightness' selector ldrum 26 to the runway selector drum 32 and insures a safe and correct-operation ofthe runway lights. The interlock insures .that the primary circuit A cannot .be closed unless -a brightness selection has rst vbeen made. It also insures that on'cea predetermined runway or group of runwayshave' been selected, no change in Vbrightness selection can be made unless the :runway selector drum 32 has vbeen returnedxto the"off position. This sequence oi operation insures that no current flowing through `primary circuit Awill be broken by tips of either brightness or runway selector relays.

As shown in Fig. 4, Vthe 'mechanical interlock consists lof a pairo'f baseplates 38 one of which is secured adjacent the end face of the brightw'hile the other is similarly securedadjacent the-end face of the runway selector drum 3'2. Keyedfto-shaft '33 of thebrightness selector drum 26"fis a disc `4I'I having cut out;

portions 4I, at spaced intervals, about theperiphery of said-disc 40. At the top face vof said disc 4I), at regularly 4spaced intervals, are other cut out portionsor indentations 42, A bracket 43 pivotally supports a ratchet arm 44, one end of which is urged counterclockwise by a spring 45 secured to said base plate 38. A rounded firm lip 46 depends from the end of the ratchet arm 44, which is urged counterclockwise by the action of theA spring 45. The lip 46 rides along the periphery of the disc 40, engaging the cut out portion 4| when the latter is juxtaposed against said lip 46.

A spring 41, bracket 48, ratchet arm 49, lip 58 and cut out portions 5| on `the disc 52 secured to the shaft 53 of the runway selector drum 32 correspond to like parts described hereinabove in connection with the brightness selector drum 26. However, instead of the indentations 42 formed in disc 48, a substantially V-shaped niche 54 is cut into the top face of the disc 52 so as to accommodate a V-shaped lug 55 that depends from one end of a rocker member 56 which is pivoted near its center on a stud 51. A lug or pin 58 depends from the other end of said rocker member 56 and rides on the top surface of the'disc 46, said lug 58 falling into one of the indentations 42 when the latter is turned to a position immediately below the lug 58.

A spring 59, an end yof which is shown suitably secured to the rocker member 56, urges thel V- shaped lug 55 against the top face of the disc 52. The rocker member 56 is pivoted so that when the V-shaped lug 55 is riding on the top face of disc 52, the pin 58 is urged against the top face of the disc 48. The V-shaped niche 54 in the disc 52 engages the V-shaped lug 55 only when the handle 3| that is keyed to the shaft 53 of the runway selector drum 32 is in the olf position.

Thus, the mechanical interlock insures that the brightness selection must be made before the runway dial 3| is turned from its off position. For by turning the dial 3| from its off position, the V-shaped lug 55 is made to ride on the top surface of the disc 52, causing the pin 58 to be locked in the indentation 42 which corresponds to the off position for the brightness selector drum 26, preventing rotation of the drum 26. This serves as a convenient and practical means for preventing a choice of runway until the required brightness for that runway has been selected.

As shown in Fig. 3, the vari-ous commutator segments 66 and electrically conducting ngers 6| are positioned relative to one another so that a finger 6| does not contact a commutator segment 60 of the brightness selector drum 26 unless the pin 58 lies in an indentation 42 corresponding to any of vthe intensity values, dim, medium or bright. There is no Contact between a finger 6| and a commutator segment 60 when the handle 21 is turned to the "o position even though the pin 58 may be resting in an indentation 42. Similarly, the fingers 62 of the runway selector drum 32 do not engage the short commutator segments 63 unless the lip 50 of the ratchet arm 49 engages or is within the immediate vicinity of the cut out portion 5| of the disc 52. Likewise, there is no contact between a finger 62 and short commutator ring 63 or long commutator ring 64 when the handle 3| for the runway selector drum 32 is in its off position.

Thus, no current passes through either drum unless a selection has beenV made, the particular selection made being shown by the lighting up of one of the indicating lamps on the panel board 25. Moreover, by using discs 4l) and 52 that have cut outs such as 4| and 5|, the person operating the handles 21 and 3| on the panel board 25 can feel the drums 26 or 32 lock into position, there being no need for a careful turning of either handle 21 or 3| such as is required in the turning of a graduated dial of a control panel, and only one hand is needed to operate the panel board 25.

Thus, the mechanical interlocking means combined with the commutator segments 66, 63, and 64 and fingers 6| and 62 on the brightness and runway selector drums 26 and 32, respectively, insure a selection of a particular brightness and a particular runway before current can pass through the primary circuit A, even if switch 31 is closed. Moreover, the particular combination of instrumentalities, namely, a novel locking means and novel drum segmentation, permit the use of a simple control panel, which a novice can learn to operate in a very short time. Another feature, as will be described and explained, consists of switch means incorporated in the runway selector drum 32 and in circuit from runway selector drum 32 to primary circuit oil breaker which prevents pick up and drop out yor" said circuit breaker while drum 32 is rotated from positions l to 5, inclusive.

Fig. 5 illustrates in detail the structure of the drums and the manner of mounting the same in panel board 25. For purposes of the present description, only the brightness selector will be described, the description of the runway selector being deemed clear from the description of the brightness selector. There is shown a rod 18 which is secured at the respective ends to the upper base plate 38 and lower base plate 1| as shown in Figure 3. Secured to this rod 1|! is a non-conducting block 12 that supports one of the selector fingers 6|. One of the pins 13 that secures said finger 6| to the non-conducting block 12 is an electrical conductor and connects with an electrical lead 14 which in turn is connected to a conducting post 15. A spring 16 is secured in the manner shown so as constantly to urge the tip 11 of nger 6| towards the periphery `of the drum 26. The conducting segment 66 protrudes beyond the periphery of the drum 2B and periodically engages the tip 11 of the finger 6|. These segments 6|! protrude from the drum 26 at different angular positions corresponding to different selections of brightness intensity, the different positions (l, 2, 3, 4) being schematically shown on the brightness selector drum in Fig. 1. The non-conducting ribs 18 form the major body of said selector drum 26, and ribs 18 being reinforced by the key stocks 16.

In Fig. 1, there are shown five short segments 63 that are positioned lon the runway selector drum 32 in the manner shown so that these segments 63 will be contacted after a particular runway has been selected and will be tripped out of the circuit just before the segment 64 corresponding to this particular runway drops out. Thus, if a change of selection from runway I to runway II is to be made, the turning of the handle 3| of the runway selector drum 32 will cause one of the ngers 62 to be disengaged from the short segment 63 while another finger 6| is still engaging the segment 64 corresponding to runway I. Thus, the short segment 63 is tripped out just before going from runway I to runway II, so that the coils of the primary circuit breaker are deenergized during the change in selection from runway I to II. The same condition applies in going from the second runway selection to the third runway selection, etc., so that the high voltage primary circuit can never be broken across the relays |1, I6, I9 and 26,'even if the switch 31 is kept closed while the runway selector drum 32 is being rotated.

rihere are various units that are self-explanatory such as the protective relay 2l in the primary circuit A and the resistors 66 in series with each of the indicating lamps when the feed lines 23 take current from avsource of power whose voltage is considerably higher than the voltage of said indicating lamps. Y

Another novel feature incorporated in the present invention provides for control from this novel runway traine control panel of the lighting of all four runways simultaneously. Airelds do not use all their airstrips for operations in a single night because planes take off or make landings against the prevailing wind. Thus, all known panels used for controlling the lighting of airfield runways provide for the lighting of only one airstrip at a time, since the lighting of moreV than one airstrip at a time for flight operations is not desirable. In the present disclosure, the runway I corresponds to a 190Q orientation of a straight runway and II corresponds to a (5W-240 orientation of another straight runway, etc. So if a southerly wind prevails at the landing held, the airstrip I would be lit for night landings or when visibility at the landing field is restricted. However, during bad weather when snow and/ or ice covers all airstrips, it is helpful to be able to light up all (in the present example, there are four) runways simultaneously so that the runways can be cleared of ice and/or snow by working parties working on all airstrips at once. Previously, attempts to clean airstrips with only one strip capable of being lighted by the control panel resulted in damage to the runway lights by the snow removal equipment as the unlighted lamps or markers were difficult to distinguish in the dark, especially when overcast skies prevail (the usual condition during steady snowfall).

In order to light all runways simultaneously, the brightness selector drum 26 is turned to the Llth position (Fig. 1) and the runway selector drum 32 is turned to the 5th position (Fig. 1), switches 22 and 3l being closed. From the diagram in Fig. 1 it will be seen that all four runways are lighted and the auto-transformer I3 is bypassed so that the maximum current goes through the lights of all four runways I, II, III and IV.

The operation of the control panel 26 which remotely controls the lighting of the runways shown in Fig. 1 is very simple. First the switch 22 is closed so that current is available for lighting the indicating lamps of the panel 25 and for energizing the relays i4 through 20. The brightness selection is made by turning the handle 2l clockwise, thus energizing the desired brightness relay. The particular runway is then selected, the operator feeling the drum 32 lock in place when a particular selection has been made just as he feels the brightness selector drum 26 lock in place when a particular brightness has been selected. The switch 31 is then closed to light the runway or runways selected, the mechanical interlock insuring that no lighting of a runway will take place unless a preliminary selection of light intensity for said runway has been made.

The present control panel prevents the possibility of damaging the sensitive selector relays used in the circuit A of the runway circuit described by providing novel interlock means between the brightness selector drum 26 and runway selector drum 32 and switch means incorporated within said runway selector drum 32. Moreover, the panel is exceedingly simple in de- 6 sign and operation, permitting almost immedi-i ate operation by a novice without endangering electrical equipment in the runway lighting circuit. Also, the present vcontrol panel provides for the lighting of all runways simultaneously,

v a feature, as was explained previously, of considerable importance when runways have to be cleaned of snow, ice or debris.

Changes can be made in the above-described embodiment of this invention without departing from the spirit and scope thereof as set forth in the appended claims.

This application is a division of the application of Malcolm H. Sheldon, Serial No. 624,621, nled October 26, 1945, for Runway Lighting Control, now U. S. Letters Patent No. 2,509,018 issued May 23, 1950.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. A mechanical interlock comprising a fra-me member, a first disc mounted on said frame member for rotation through 360 of freedom, said disc having a V-shaped notch insa face thereof and a plurality of notches in the rim thereof, a second disc mounted on said frame l member for rotation through 360"I of freedom,

said second disc having a plurality of dimples in a face thereof, said dimples being equiangularly spaced and equidistant radially from the center of said disc, and a plurality of notches in the rim thereof, a rockable member supported on said frame member in selective contacting relation with said faces of said discs, said rockable member carrying a. spring urging said member towards engagement with said first disc and having conformable projections at its ends adapted respectively to engage said V-shaped notch and one of said dimples, and a pair of spring-tensioned ratchet arms mounted on said frame member, each of said arms having a rounded lip projection engageable by the rim-notches of one of said discs.

2. A mechanical interlock comprising a frame member, a first disc mounted rotatably on said frame member and having a V-shaped notch in a face thereof and a plurality of notches in the rim thereof, a second disc mounted rotatably on said frame member and having a plurality of notches in the rim thereof and a plurality of dimples in a face thereof, said dimples being equiangularly spaced and equidistant radially from the center of said disc, a rockable member supported on said frame member in selective contacting relation with said faces of said discs, said rockable member carrying a spring urging said member towards engagement with said first disc, and having conformable projections at its ends adapted respectively to engage said V-shaped notch and one of said dimples, and a pair of spring-tensioned ratchet arms mounted on said frame member, each of said arms having a rounded lip projection engageable by the rim notches of one of said discs.

3. A mechanical interlock comprising a frame member, a rst disc mounted rotatably on said frame member and having a notch in a face thereof and a plurality of notches in the rim thereof, a second disc mounted rotatably on said frame member and having a plurality of notches in the rim thereof and a plurality of indentations in a face thereof, said indentations being equiangularly spaced and equidistant radially from the center of said disc, a rockable member supported on said frame vmember in selective contacting relation With said faces of said discs, said rockable member .carrying a spring urging said member towards engagement with said rst disc, and having projections at its ends adapted respectively to engage the face notch of said rst disc and one of said indentations, and a pair of spring-tensioned ratchet arms mounted on said frame member, each of said arms having a projection engageable by the rim notches of one of Y said discs.

4. A mechanical interlock comprising a frame member, a rst disc mounted rotatably on said frame member and having a notch in a face thereof and a plurality of notches in the rim thereof, a second disc mounted rotatably on said frame member and having a plurality of notches in the rim thereof and a plurality of indentations in a face thereof, a rockable member supported on said frame member in selective contacting relation with said faces of said discs, said rockable member carrying a spring urging said member towards engagement with said first disc, and having projections at its ends adapted respectively to engage the face notch of said first disc and one or" said indentations, and a pair of sprng-tensioned ratchet -arms mounted on said frame member, each of said arms having a pro* jection engageable by the rim notches of one of said discs.

8 f5. A mechanical interlock comprising a frame member, a first disc mounted rotatably on said frame member and having a notch in a face thereof and a plurality of notches in the rim thereof, a second disc mounted rotatably on said frame member and having a plurality of notches in the rim thereof and a plurality of indentations References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 548,599 Valley Oct. 22, 1895 560,751 Potter May 26, 1896 611,090 Zweigbergk Sept. 20, 1898 677,027 Garrett June 25, 1901 708,724 Merrick Sept. 9, 1902 2,509,018 Sheldon May 23, 1950 

